Actually it's not basic nor standard, considering I can send a message from my phone's telephone number when my telephone isn't even on... so to say it's one of the most basic concepts is utter BS.... But thanks for trying!
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So if you're going to a restaurant you've never been to and find their website to be "http://geocities.com/tomsdiner76" do you take that restaurant as seriously as if the result came back :"http://www.tomsdiner.com" ??? If so, your feelings are against the norm of those on the internet. Having quality, personalized domains is what differentiates a perception of cheap vs quality. When it costs literally $6.95 a year to have your own domain name, having an @hotmail.com or other free email providers is seen (at least by professionals in the tech industry) as off-putting. The one exception seems to be gmail for whatever reason...
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I guess the way I look at it is I wouldn't carry around my laptop in a plastic Apple bag, I buy a nice case for it so it looks more respectable. I wouldn't print a resume on plain copy paper, because I buy a slightly heavier stock, maybe slightly darkened paper, because I want it to look more respectable. I don't spend $850 on a phone and then throw a free yahoo.com email on it when I can spend $10 a year and have a more reliable, professional looking email address with my name (or business name) as the domain.
Perception isn't important to everyone. Plenty of people drive around dirty cars with fast food wrappers in the back seat, or wear shoes that are dirty and don't care to wash them... I guess different strokes for different folks as they say.